Rotary pump



March 9, 1937. c. J. WESTIN 2,073,188

ROTARY PUMP Filed May 28, 1934 2 Sheets-Sheet l March 9, 1937. c, wEs2,073,188

ROTARY PUMP Filed May 28, 1934 2 Sheets-Sheet 2 Illllllll i L wuum r\ 663 F WI Charlasdhs fipm,

Patented 9, 1937 PATENT OFFICE ROTARY PUMP Charles J. Westin,Philadelphia, Pa., assignor to F. J. Stokes Machine Company, acorporation of Pennsylvania Application May 2a, 1934, Serial No. 728,006

2 Claims.

This invention relates to improvements in mechanical gas pumps andparticularly to the type of pump used either as compressors or as vacuumpumps. One form of this type of pump 5 is shown and disclosed in U. S.Letters Patent No. 1,899,904, granted to O. S. Sleeper and C. J. Westinon February 28, 1933. Another form is disclosed in my co-pendingapplication Serial No. 724,974, filed May 10, 1934, now Patent No.

One object of my invention is to provide new and improved means forautomatically separating the air and gas from the sealing medium..

Another object is to provide improved means for condensing the vaporscoming through the pump or the vapors created by the rapid flow and thepressure in the pump.

It is also an object of my invention to arrange the de-gasing andde-vaporizing means so that the sealing medium is automatically returnedto the reservoir for recirculation.

A further object of my invention is to provide a novel separatorstructure for separating vaporized oil or liquids from the exhaustgases, the

separator being formed as an independent unit mounted upon the base ofthe pump andhaving a duct for returning the condensed or separated oilto the ofl reservoir within the base of the pump.

By means of these and other improvements which will be understood fromthe specification, I obtain several advantages: such as, increasedcapacity to handle larger volumes of gas in the same space of time; alower operating temperature; a higher vacuum for the same operatingspeed; a saving in the amount of lubricating and sealing oil used; andin general a cleaner operating machine.

In order to operate at practical efficiency, all

moving parts must be machined to close fits or small clearances so thatthey will cooperate throughout the cycle 'with'the lubricating andsealing medium in forming a perfect or nearly perfect seal between thehigh and low pressure sides of the pump. It is of utmost importance thatthe sealing medium entering the pump system should be demulsified orfreed of all air, gases or water. Thesealing medium, of course, isbrought in close contact with all the moving parts of the pump andshould therefore embody such properties as make it suitable as alubricating medium. The sealing-lubricating medium, which hereafter willbe referred to merely as oil will therefore serve a dual purpose andshould have certain desirable properties, such as low percent- (Cl.23(l207) "ly circulating from atmospheric pressure, through age ofvolatile constituent and a low demulsibil ity. Oil will, however, absorbgas in considerable quantities, particularly when churned around withgas under pressure as is the casein machines of the type here described.As the oil is continualthe low pressure stage approaching the highpressure, and being expelled at high pressure into atmospheric pressureagain, it is bound to become more and more polluted, thereby graduallydem creasing the efliciency of the pump. Furthermore, the oil and gasare discharged at considerable speed and pressure through comparativelysmall discharge ports, and this has a tendency to vaporize or atomizesome of the oil, which vapors 15 or atomized oil would pass 01! with thegas and be lost unless properly trapped and separated from the freegases before these reach the outside space.

In medium sized and larger pumps of for example 50 cubic feet capacityand over, I find that, on account of the large volume of gases handled,the separator should be of considerable size to effectively devaporizethe gases. For this reason it is preferable to place the separatoroutside the housing or oil reservoir. It is also a convenience inmanufacture.

I have also found it very helpful to chill the gases as they enter theseparator so as to cool and condense out the vapors entrained in the 30hot gases.

The principles of construction and novel arrangement of parts will bereadily understood by reference to the annexed specification and draw-IDES. 35

In the drawings, Figure 1 is a vertical view of my invention showing thepump with the exhaust separator, the pump being shown in full sectionand the separator in part section;

Figure 2 is a vertical section showing the de- 40 tails of constructionof the separator unit;

Figure 3 is a sectional view of Fig. 2 taken along line 33; and

Figure 4 is a sectional view of Fig. 2 taken along line 1-4. 15

Referring to the drawings, there is shown a rotary pump having a housingl0 mounted on a hollow base i I. In the housing is formed a cylinder l2,closed at both ends by end-plates, and partially surrounded by a spacel3 adapted to 50 receive water or other cooling medium, and having apassage l4 for conducting the discharge gases and oil from the dischargevalve into hollow base II. The housing I0 is extended at the top to formaninlet compartment l5 of rectangular outline connected directly to andextending the full length of cylinder l2 and being closed at both endsby extensions on the cylinder endplates. The inlet compartment II has alateral extension Ila to which an intake connection I. is secured.Alongside the intake compartment i5 in the extension of housing II isformed the outlet compartment with suitable accommodations for theoutlet valve assembly I! arranged over a row of cylindrical dischargeports is connecting the outlet compartment I! with the cylinder I2. Onewall of compartment I1 is formed as a cover-plate 2I which is madehollow so as to provide a free passage 2| for the discharged gases andsealing medium into the corresponding passage of the housing to which itis connected. The inside wall 22 of the passage 2| in coverplate 20 ismade of such height that it will act as a dam to retain a sumcientamount of the sealing medium in the outlet compartment l'l to completelycover or submerge the outlet valve arranged over ports is, only theexcess of sealing medium spilling over the dam 22 and escaping down intothe base ll together with the free gases and vapors. The details of theoutlet valve construction are fully described and claimed in mycopendlng application Ser. No. 724,974, filed May 10, 1934, now PatentNo. 2,070,151.

Through the center of cylinder I2 is mounted a shaft 23 with supportingbearings in the cylinder end-plates and driven from any suitable sourceof power. Keyed or otherwise fastened to shaft 23 is the rotaryeccentric 24 which carries on the outer surface the tube-shapedoscillating piston 25. A slide valve 26 is fastened to the piston 25.

by means of a hinge 21 of such construction as to provide a gas-tightand flexible connection between piston 25 and valve 23. Thisconstruction is described in greater detail and is claimed in theSleeper and Westin patent referred to above. Through this connection,valve 26 receives a reciprocating rectilineal motion in the rectangularinlet compartment l5, and as the valve 26 slides back and forth, theinlet ports 28 in the valve connect the inlet compartment l5 with thecylinder 12 at the proper time in the cycle.

All discharge gases, vapors and oil must pass over dam 22, throughpassages 2| and I4 down into the oil reservoir II in the base II. Thisreservoir is of such construction as to provide ample space for thestoring of the sealing medium or oil and also provides head-room or airspace above the oil level for the gases to pass on to the separator 53mounted upon a lateral extension Ila of the base ll. Connections aremade from an oil filter 30 in the reservoir 4!, through pipe line 3| toa valve 32, through which clean oil is drawn into the reciprocatingvalve chamber for lubricating and sealing purposes. A cooling coil 33 isusually provided in reservoir 4| and materially aids in keeping theoperating temperature of the pump low by cooling the oil. Coil 33 isconnected to the space I3 by pipe 3| for circulation of water throughthe coil.

A separator and other baiiie arrangement may be used in the base but toget satisfactory separation these parts would have to be so large as tomake the size of the base out of proportion. I, therefore, prefer toplacea separator 53 of suitable size outside of the housing or reservoirand lead the gases and vapors from the reservoir into the separatorthrough the duct 52 formed by extension Ila on which the separator issupported.

It is desirable that only the gases are allowed to pass of! while theoil entrained in the gases or vaporized during the cycle of operation isseparated out and returned to the reservoir for recirculation. Withoutproper means for perfect separation a considerable volume of vapors passout into the surrounding room, particularly when starting the pump orwhen operating at low pressures, thus filling the room with disagreeablesmoke. While, of course, it is possible to eliminate the smoke nuisanceby connecting the discharge to the outside of the building, this doesnot prevent the resulting waste of good lubricating and sealing oil.

The above diillculties and losses have been eliminated through the useof separators constructed according to my invention. The separatorconstruction is formed as a unitary structure bolted to a flange on baseextension Ila. The separator consists of a casing 53, which may be ofany outline, but for the sake of simsimplicity it is here shown as acylinder. The bottom 54 has two openings communicating with the hollowbase II. The large opening 56 provides free passage for gases and vaporsfrom outlet duct 52 into the separator. It will be noticed that a rim 5!is provided around opening 56. This rim forms an annular reservoirsurrounding the inlet opening 58 and serves the purpose of keeping theseparated oil from' running back into the duct 52 where the current ofgases may tend retard the flow back into the reservoir or might pick upsome additional 011 particles. The oil flows back through the returnpassage or opening 55, which has a pipe 58 leading down into thereservoir 4| well below the oil level.

The top or head 53 of the separator has an exhaust connection 60 whichmay be a pipe line or duct through which the obnoxious gases may bedischarged outside the building.

The separator casing may be of any suitable diameter and height toaccommodate the proper size and number of shelves or baiiies necessaryfor proper separation. The spacing of the baiiies should be such thatthe current of gases will pass through at a comparatively rapid rate offlow without creating any noticeable back-pressure. At the same time itis desirable to arrange the baflles so that the current will strikeagainst the baflie-surfaces, causing some of the entrained oil to adhereto these, as well as force the current to make short bends or turnswhere the heavier oil particles are thrown against each other and uniteinto drops which fall down onto the sloping bailie surfaces below.

The whole separator casing may be filled with cooled baflies of thehollow-shelf type or with a combination of plain and cooled type'asshown in Figures 2 to 4. A plain type of bailie is one of the simpleplate construction as compared with the hollow box-like shelf or baillewhich will be referred to as cooling shelves or cooling baiiies.

In the construction shown, the casing 53 is provided with a number ofbaflies arranged across the casing, extending alternately from oppositesides of the casing past the middle thereof, thereby forming a zigzagpath for the gases passing through the separator.

The first few shelves or baiiies 5|, 52 and 63 adjacent the inletopening 55 are made hollow, and have connections so that a coolingmedium, such as water, may be circulated through them to chill the gasesand vapors as they enter the separator. The various shelves Si, 62 and63 are connected by communicating passages such as the hollow partitionsor ducts 54 and a to Ben mit the cooling fluid to be passed from onebaille to another. The water enters at 65, circulates through the hollowbattles and is discharged at 66. The edge 12 of the baille which comesnearest the open passage will be referred to here as the front of thebattle or shelf.

It will be noticed that the baflles are mounted at an angle with thehorizontal, sloping down diagonally towards the front as well as towardsone side of the front edge. The reason for this slope or incline is toguide the oil collecting on top of the shelf towards one side where itwill run down along the wall of the separator casing instead of, asotherwise might happen, anywhere and everywhere along the front edge inthe path of the current. The angle of slope may be any. suitable angleas long as the slope is suflicient to make the oil run oif fast enoughto prevent the forming of a drop. It will be noticed from the drawingsthat the first shelf BI is supported in the separator so that it has anincline slope from right to left or from the casing to the right slopingdown past the center to the front. At the same time it should also benoted that the far side of the shelf is higher than the near side, thatis, the shelf is sloping from the far side wall to the near side walland thus has a slope in two directions. The other shelves and battlesare arranged in a similar manner.

Another novel feature is the provision of a gutter 81 under the frontedge of each baiile. The current of gases and vapors will strike againstthe bottom of the battle and a portion of the;

entrained oil will adhere to this surface. When a-suilicient quantity ofoil has accumulated on the surface, this will flow towards the frontand, instead of dropping off in the path of the current, will becollected in the gutter and run to the side and then down the wall ofthe casing. Thus, means are provided to prevent reabsorption of any oilwhich has been removed from the gases. It will be understood that thegutters 61 are not essential but will improve the efliciency of theseparator.

The plain baiiles consist of flat plates 68 which may or may not havegutters 69 of similar construction to 61 and serve the same purpose asdescribed for the gutters on the cooling baflies. I prefer to arrangethe plain bailles 68 according to the same principles described for thecooling bailles, that is, with the surfaces suitably sloping towards thefront and one side in order to provide for the proper draining of theoil. l gr certain vacuum work I have found that theplain bailes 68 arequite satisfactory, and, of course, considerably cheaper to manufacture,and therefore a separator having only plain baflles would mean aconsiderable economy.

It will be observed that in the construction shown, the exhaust gasesfrom the pump first pass from the outlet valve chamber l'l down throughthe passage ll into the air space above the oil reservoir 4| in the baseof the pump, and then out through the separator 53. BY this arrangement,the gases are first freed of all oil which may be separated by gravity,and are par-. tially cooled by passing over the oil reservoir beforethey reach the separator. In this way, a partial separation takes placeas the gases flow through the air space above the reservoir, and I theseparator acts with greater emciency in completing the separationprocess.

I have herein described the principle of my invention and illustrated apreferred embodiment thereof. Various modifications will occur to thoseskilled in the art, and I desire it to be understood that allmodifications which fall within the terms of the appended claims are tobe considered as falling within the scope of my invention.

What I claim is:

1. In combination, a hollow base provided with an oil reservoir therein,a vacuum pump mounted on the top of said base, a gas inlet in said baseon one side of said pump, a gas outlet in said base on the other side ofsaid pump, a conduit connecting the pump outlet with the gas inlet insaid base, a unitary separator detachably mounted on said base having aninlet arranged over the gas outlet on said base and having an outletcommunicating with the atmosphere, said separator being so constructedthat the separated oil is maintained substantially out of the path ofthe discharge gases and embodying a reservoir for collecting all of theseparated oil, and a conduit carried by said separator and extendingfrom said separator reservoir to a point below the surface of the oil insaid base reservoir for returning separated oil to said base reservoirout of the path of said gases, whereby the exhaust gas discharged intothe atmosphere is substantially free from entrained oil and the oilsupply is thereby conserved.

2. In combination, a hollow base provided with an oil reservoir therein,a vacuum pump mounted on the top of said reservoir, a gas inlet and agas outlet formed in said base and communicating with the air spaceabove said oil reservoir, means for passing exhaust gases from said pumpinto said gas inlet, a unitary separator detachably mounted on said basehaving an inlet arranged .over the gas outlet in said base and having anoutlet communicating with the atmosphere, said separator being soconstructed that the separated oil is maintained substantially out ofthe path of the discharge gases and having an annular reservoirsurrounding its inlet opening for collecting all of the separated oil,and a pipe secured to and carried by said separator for returning oilfrom said annular reservoir to a point below the surface of the oil insaid base reservoir out of the path of said gases, whereby the exhaustgas discharged into the atmosphere is substantially free from entrainedoil and the oil supply is thereby conserved.

CHARLES J. WEBTIN.

